Tuesday, December 13, 2022

The fine print (that's continually overlooked)

Obviously, while she is getting quite well known, not enough people have seen Sabine Hosenfelder's video from last year about the huge amounts of energy that are needed to drive the systems needed to get "net energy gain" in experimental fusion.  Here's a link to it again.

Oh, and look, the Washington Post story about the "big breakthrough" at one facility, has this fine print, which really, honestly, should be reflected more in the headlines:

“If it’s what we’re expecting, it’s like the Kitty Hawk moment for the Wright brothers,” said Melanie Windridge, a plasma physicist and the CEO of Fusion Energy Insights. “It’s like the plane taking off.”

Does this mean fusion energy is ready for prime time?

No. Scientists refer to the current breakthrough as “scientific net energy gain” — meaning that more energy has come out of the reaction than was inputted by the laser. That’s a huge milestone that has never before been achieved.

But it’s only a net energy gain at the micro level. The lasers used at the Livermore lab are only about 1 percent efficient, according to Troy Carter, a plasma physicist at the University of California, Los Angeles. That means that it takes about 100 times more energy to run the lasers than they are ultimately able to deliver to the hydrogen atoms.

So researchers will still have to reach “engineering net energy gain,” or the point at which the entire process takes less energy than is outputted by the reaction. They will also have to figure out how to turn the outputted energy — currently in the form of kinetic energy from the helium nucleus and the neutron — into a form that is usable for electricity. They could do that by converting it to heat, then heating steam to turn a turbine and run a generator. That process also has efficiency limitations.

All that means that the energy gain will probably need to be pushed much, much higher for fusion to actually be commercially viable.

At the moment, researchers can also only do the fusion reaction about once a day. In between, they have to allow the lasers to cool down and replace the fusion fuel target. A commercially viable plant would need to be able to do it several times per second, says Dennis Whyte, director of the Plasma Science and Fusion Center at MIT. “Once you’ve got scientific viability,” he said, “you’ve got to figure out engineering viability.”

And yet the article still ends on a rather misleading note:

Current fusion experts argue that it’s not a matter of time, but a matter of will — if governments and private donors finance fusion aggressively, they say, a prototype fusion power plant could be available in the 2030s.

“The timeline is not really a question of time,” Carter said. “It’s a question of innovating and putting the effort in.”
The article didn't even mention the other well known problems of practical fusion power:  how to deal with the physical container getting radioactive from neutrons (or at least, at a slow enough rate that it doesn't become prohibitively expensive), the supply of tritium issue, and other matters which are detailed at links in my post of 2019.

It just seems that people are having a hard time believing that scientists involved in this type of research are prone to exaggerated optimism.  Why are there so few articles exploring this in depth in the mainstream media?? 

 

 

 

 

1 comment:

John said...

Thanks for the clarification Steve. I was wondering about the net energy release given how dishonest previous reports have been. Given your extracts this looks like just another GIMME MONEY nonsense by bods. Happens all too often.